1. Field of the Invention
The present invention relates to systems for improving the longevity of wooden posts by preventing rot and decay thereof and more particularly to a device which is attachable to the lower end of such a wooden post to feed preservative to the post as needed.
2. Description of the Prior Art
Wooden posts, such as those made of cedar and redwood, are used extensively in outdoor locations where they are exposed to rot and decay. Such posts are typically used in fencing systems, to support signage, or in other structural environments, and in most cases the wooden posts are embedded in the ground where decay is most likely to occur.
Decay occurs as a result of fungus growth, but fungus will only grow under certain environmental conditions. Most favorable fungus growth occurs as a result of the four following variables: (1) Heat (optimum range--68.degree. to 95.degree. Farenheit); (2) Moisture (20% or greater); (3) Oxygen; (4) Food (wood fibers/cellulose and wood sugars).
Moisture and adequate oxygen from soils provide extremely favorable decay conditions. Contrary to popular belief, there is no such thing as "dry rot." Dry wooden posts do not rot, thus explaining the above-ground longevity of most dry wooden structures.
Decay fungus will not readily grow if one or more of the four above-listed conditions is eliminated. The first three conditions, namely heat, moisture and oxygen, cannot be effectively controlled under real conditions. However, the fourth condition, food, can be affected. The introduction of preservatives into the wood poisons the cellulose and wood sugar, thereby depriving the decay fungus of its food supply and "preserving" the wood from rot.
Preservatives can be introduced into the wood in numerous ways. Pressure and vacuum treating methods have been developed whereby entire pieces of dried structural wood are treated with a preservative in pressure vessels. In such methods higher than atmospheric pressures, artificially created partial vacuums, and/or submergence of the wood in preservative chemicals are used to increase preservative penetration during relatively short-term treatment processes. The effectiveness of the treatment is directly proportional to the residence time of the wood in the treatment process. These processes are generally expensive and typically cause a discoloration of the natural wood. Other competitive wood preserving techniques include dip treating, wrap-around, spray, and brush-on coatings of preservative. The primary limitations with these techniques is a lack of penetration of the preservative into the wood. For this reason, these techniques are not satisfactory for use with wooden posts that are to be embedded in the ground for long periods of time.
Other systems have been devised for use with wooden posts that are embedded in the ground whereby a supply of preservative is retained in a pocket surrounding the wooden posts. Examples of such systems are disclosed in U.S. Pat. No. 1,001,144 issued to J. D. Hilliard; U.S. Pat. No. 868,953, issued to T. B. White; and U.S. Pat. No. 837,820 issued to H. P. Folsom and H. Jones.
These systems are of particular interest due to the fact that they are adapted to surround a wooden post in a below-ground location and in one instance, namely the system disclosed in the Hilliard patent, means are provided for adding preservative to the system on a periodic basis.
One significant drawback with the aforenoted patented systems for preserving wooden posts is that the preservative is disposed around the cylindrical or longitudinal walls of the post and not to the end grain of the post where it is felt that the most satisfactory or adequate penetration of the preservative is obtained.
It is therefore a primary object of the present invention to provide a system for prolonging the life of wooden posts that are embedded in the ground in a manner that is more effective and efficient than has previously been known.
It is another object of the present invention to provide a system for preserving wooden posts by continuously delivering preservative to the exposed lower end of the post where it has been determined that optimal absorption of the preservative takes place.